The present invention relates generally to railroad right-of-way installation or maintenance machines, and specifically to a railway plate inserter for applying rail plates to rail ties, and a method of inserting the plates.
Conventional railroad track consists of a plurality of spaced parallel wooden ties to which are attached a pair of spaced rail tie plates. Each tie plate is configured to rest on the upper surface of the tie and includes holes for receiving spikes or screws, as well as a canted seat or a cradle formation for receiving the bottom or base of the steel rail. Since two rails make up a railroad track, there are a pair of spaced tie plates on each tie. Some of the spikes are used to secure the tie plate on the tie and others are used to secure the base of the rail to the tie plate cradle.
When laying a new railroad track, replacing worn ties, or when laying new rails on a pre-existing railroad track, it is necessary to provide and position tie plates on the railroad ties. One plate is required for each side of each tie. The plates are initially placed adjacent the track, either by a crane or by a work gang. Then, the plates are placed onto the top surface of the tie. Subsequently, the plate must be positioned to the proper location on the tie to receive the rail.
Proper positioning of the plate on the tie requires the work gang to center the plate on the width direction of the tie, and position the plate under the rail to receive the bottom portion of the rail in the recess of the plate. In the past, the work gang has had to lift the rail or the tie in order to properly position the plate. It will be appreciated that the manual placement involves high labor costs, inconsistent accuracy of placement, and a time consuming process.
To avoid on the job injuries, especially those involved with handling tie plates, which typically weigh approximately 18-40 pounds and are awkward to manipulate, railways have attempted to mechanize the plate insertion process as much as possible. Such systems have not been widely accepted by the railroads because of the relatively complicated mechanisms involved in performing the insertion.
Additionally, there is inaccuracy in some of the insertion machines, particularly when there are irregularities in plate sizes and shapes. For example, the plates used on a curve in the track are larger than the plates used on a straight stretch of track. Deviations of as little as ⅜ of an inch in the plate is significant in terms of an insertion machine being able to properly place the plate. Due to these variations, frequent readjustment of settings is required to accommodate different sizes and shapes of plates.
Further, in many instances the insertion of the new plate is impeded by railway ballast. Conventional mechanisms have no way to remove unwanted ballast particles from the top surface of the tie.
Railroad installation and maintenance machines typically include a frame which is either self-propelled or towable along the track, and a plate inserter configured to perform the maintenance task. Such devices typically have a travel position, where the portion of the plate inserter is held sufficiently above the track to avoid damage by obstacles including the track itself, and a work position. During operation in the work position, the units typically move between a loading position for loading the part, and a track engaging position for applying the repair part. To avoid damage to the mechanisms, such units are designed for operation so that either travel is prohibited when these mechanisms are in the latter two positions, or the mechanisms automatically rise to the travel position when the unit begins to move to the next location.
While protecting the plate insertion mechanisms, these conventional operational precautions tend to take time and limit productivity of the plate insertion process. Further, in cases where the plate inserter is one of a chain of maintenance machines, the productivity of the overall maintenance of the railroad is limited as measured by the rate of the slowest unit.
Accordingly, there is a need for an improved plate inserter which reduces the manual handling of plates during the plate insertion process.
There is also a need for an improved plate inserter which enables a high frequency of plate insertions while protecting the plate inserting mechanisms.
Further, there is a need for an improved plate inserter which is accurate despite variations in the track, and which does not require readjustment to accommodate the variations in the track.